Schneider Electric PowerLogic PM5300 Series Especificaciones descargar pdf (Pagina 55)

63230-507-201A1 Power Meter 750

03/2007 Appendix C—Instrument Transformer Wiring: Troubleshooting Guide

APPENDIX C—INSTRUMENT TRANSFORMER WIRING:

TROUBLESHOOTING GUIDE

Abnormal readings in an installed meter can sometimes signify improper

wiring. This appendix is provided as an aid in troubleshooting potential

wiring problems.

SECTION I: USING THIS GUIDE The following sections contain “Case” tables showing a variety of symptoms

and probable causes. The symptoms listed are “ideal,” and some judgment

should be exercised when troubleshooting. For example, if the kW reading

is 25, but you know that it should be about 300 kW, go to a table where

“kW = 0” is listed as one of the symptoms.

“Section II: Common Problems for 3-Wire and 4-Wire Systems ” addresses

symptoms and possible causes that occur regardless of system type. Check

this section first. If the symptoms are more complicated, proceed to “Section

III: 3-Wire System Troubleshooting” or “Section IV: 4-Wire System

Troubleshooting” as is appropriate.

Because it is nearly impossible to address all combinations of multiple

wiring mistakes or other problems that can occur (e.g., blown PT fuses,

missing PT neutral ground connection, etc.), this guide generally addresses

only one wiring problem at a time.

Before trying to troubleshoot wiring problems, it is imperative that all

instantaneous readings be available for reference. Specifically those

readings should include the following:

• line-to-line voltages

• line-to-neutral voltages

• phase currents

• power factor

• kW

• kVAR

• kVA

What is Normal? Most power systems have a lagging (inductive) power factor. The only time

a leading power factor is expected is if power factor correction capacitors

are switched in or over-excited synchronous motors with enough capacitive

kVARS on-line to overcorrect the power factor to leading. Some

uninterruptable power supplies (UPS) also produce a leading power factor.

"Normal" lagging power system readings are as follows:

• Positive kW =

• Negative kVAR =

• kVA (always positive) =

•

= lagging in the range 0.70 to 1.00 (for 4-wire systems, all

phase PFs are about the same)

• Phase currents approximately equal

• Phase voltages approximately equal

(

× I

3Φ Avg

× PF

3Φ Avg

)× 1000⁄

kVA)

kW)

(–(()1000⁄

× I

3Φ Avg

×)1000⁄

(

3Φ Avg

1 2 ... 50 51 52 53 54 55 56 57 58 59 60 ... 67 68

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